A typical burner for a gas-turbine engine is shown in FIG. 1. This is taken from U.S. Pat. No. 5,319,935 assigned to Rolls-Royce plc and issued on 14 Jun. 1994. The burner comprises a cylindrical casing 1 attached to a base assembly 2, on which is mounted a radial swirler assembly consisting of first swirler vanes 3 and second swirler vanes 4. These vanes are separated by a flow divider 5. Air enters the swirler assembly in a radial direction, while fuel enters through holes 6 in fuel conduits 7. The resulting swirling fuel and air is guided in two parts by the flow divider 5 into a fuel and air mixing zone 8, the resulting fuel-air mixture then being combusted in a combustion zone 9.